1. Field of the Invention
Adjustable limit snap gauges are very widely used for quickly determining if the outside diameter of machined parts are within allowable tolerance limits. Checking and calibration of such snap gauges is a time consuming and tedious operation. The present invention is concerned with an adjustable master setting gauge which makes possible the quick and accurate checking and calibration of snap gauges.
2. Prior Art
Any number of height gauge fixtures are well known in the prior art. Typical of such gauges are those described in U.S. Pat. Nos. 2,440,710 and 2,544,004 and in the brochure entitled PLA-CHEK published by the Cadillac Gage Co. of Warren, Michigan in 1970. Briefly, the prior art gauges include a base with an elongated open-sided column extending upwardly therefrom, a micrometer head atop the column and a bar extending from the micrometer head to the base, the bar having a plurality of equally spaced ridges annually upraised therefrom. Such gauges as are known to the prior art are generally extremely accurate but are often not convenient for use with the typical industrial snap gauges. In particular snap gauges, and especially larger snap gauges, are often too large to fit between the equally spaced ridges which are upraised from the bars of the prior art snap gauges. Further, even if the snap gauges are small enough to fit between adjacent ridges, it is generally somewhat inconvenient for the operator to fit the snap gauge up against the bar of the height gauge.
Accordingly, it has been customary to not make use of highly accurate micrometer height gauges for checking the settings of snap gauges. Instead, snap gauges are generally checked for accuracy and recalibrated using one or more very accurately machined blocks. Generally more than one block is necessary and the blocks are stacked one upon the other until the precise and exact thickness setting of the gauge is reached. Choosing the correct combination of blocks to obtain the desired dimension is time consuming and retaining the blocks in a stacked position while setting the gauge is extremely tedious and difficult, particularly on larger snap gauges. Frequently a manufacturer will have thousands of snap gauges and many man hours are consumed just in the periodic checking and calibration of the snap gauges.
Accordingly, it is the object of the present invention to provide an adjustable master setting gauge with all of the accuracy of a micrometer height gauge and which can be conveniently and quickly used to check and calibrate snap gauges of many sizes.